Differences in how some women with breast cancer respond to tamoxifen therapy may be explained in part by differences in gene activity, suggests a study in the Journal of the National Cancer Institute.

Susan Nowell, of the U.S. Food and Drug Administration's National Center for Toxicological Research, and her colleagues examined survival outcomes and activity of a gene called SULT1A1, which is involved in tamoxifen metabolism, among 160 women with breast cancer who received tamoxifen and 177 women with breast cancer who did not receive tamoxifen.

Women who received tamoxifen and had two copies of the SULT1A1 low-activity gene had roughly three times the risk of death as those who had at least one copy of the normal gene. Among patients who did not receive tamoxifen, there was no association between survival and the SULT1A1 genotype.

SOURCE:
Journal of the National Cancer Institute, November 6, 2002